Journal articles on the topic 'Aero-Structural coupling'
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1
Zuo, YingTao, ZhengHong Gao, Gang Chen, XiaoPeng Wang, and YueMing Li. "Efficient aero-structural design optimization: Coupling based on reverse iteration of structural model." Science China Technological Sciences 58, no. 2 (December 29, 2014): 307–15. http://dx.doi.org/10.1007/s11431-014-5744-5.
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Yang, Wenjun, Huiqun Yuan, and Tianyu Zhao. "Multi-field coupling dynamic characteristics based on Kriging interpolation method." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 6 (May 16, 2016): 1088–99. http://dx.doi.org/10.1177/0954410016648350.
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Multi-field coupling problems are taken more and more attention mainly because of the higher requirement of load, efficiency, and reliability in aero-engine operation. This research takes an aero-engine compressor as the research object, 3D flow field and structural models are established. For the method of cyclic symmetric, single-sector model is selected as the calculation domain. Considering the influence of former stator wakes, compressor flow field is simulated. The article analyzes the distribution law of unsteady aerodynamic load on rotor blade. Based on Kriging model, load transfer of aerodynamic pressure and temperature is achieved from flow field to blade structure. Then the effects of centrifugal force, aerodynamic pressure and temperature load are discussed on compressor vibration characteristic and structural strength. The results show dominant fluctuation frequencies of aerodynamic load on rotor blade are manly at frequency doubling of stator–rotor interaction, especially at one time frequency (1 × f0). Magnitude and pulsation amplitude on pressure surface are far greater than that on suction surface. Load transfer with Kriging model has a higher precision, it can meet the requirement of multi-field coupling dynamic calculation. In multi-field coupling interaction, temperature load makes the natural vibration frequencies decrease obviously, centrifugal force is the main source of deformation and stress. Bending stress induced by aerodynamic pressure and temperature load can counteract part of bending stress induced by centrifugal force. However, temperature load causes the maximum displacement of blade-disk system to increase.
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Chudý, Peter, and Vladimír Daněk. "DYNAMICS OF AN ELASTIC AIRPLANE." Aviation 9, no. 1 (March 31, 2005): 8–13. http://dx.doi.org/10.3846/16487788.2005.9635890.
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This paper presents the work performed by the Institute of Aerospace Engineering at the Brno University of Technology. The purpose of the project was to compare the results obtained from classical analytical solutions and a complex numerical simulation of an airplane's aero elastic response. Compared to the analytical solution, which reduces the entire process to a straightforward manipulation with time‐proven graphs and tables, the numerical simulation offers a more complex description of the dynamic processes. A complex simulation, in contrast to the analytical solution providing us with only one estimated parameter, allows monitoring selected quantities in the time domain, thus giving us a tool for a visual qualification of the investigated process. In the past, dynamic aeroelastic properties were estimated utilizing simplified stick beam models. The desire for more complex aero elastic simulations led to the concept of the advanced aero elastic model, coupling advanced 3D structural FEM models with proven aerodynamic theory in the form of the DLM panel method.
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Ma, Yingqun, Qingjun Zhao, Kai Zhang, Meng Xu, and Wei Zhao. "Effects of mount positions on vibrational energy flow transmission characteristics in aero-engine casing structures." Journal of Low Frequency Noise, Vibration and Active Control 39, no. 2 (May 17, 2019): 313–26. http://dx.doi.org/10.1177/1461348419845506.
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The main goal of the study is to apply the structural intensity method to analyze the effects of positions of the main-mount and the sub-mount on the vibrational energy flow transmission characteristics in aero-engine casing structures, so as to attenuate the vibration of the casing and the whole aero-engine. Structural intensity method, indicating magnitude and direction of the vibrational energy flow, is a powerful tool to study vibration problems from the perspective of energy. In this paper, a casing-support-rotor coupling model subjected to the rotor unbalanced forces is established by the finite element method. Formulations of the structural intensity of a shell element and the structural intensity streamline are given. A simulation system consisting of the finite element tool and the in-house program is developed to carry out forced vibration analysis and structural intensity calculation. The structural intensity field of the casing is visualized in the forms of vector diagram and streamline representation. The vibrational energy flow behaviors of the casing at the rotor design rotating speed are analyzed, and the vibrational energy flow transmission characteristics of the casing with different axial positions of the main-mount and the sub-mount are investigated. Moreover, some measures to attenuate the vibration of the casing are obtained from the numerical results, and their effectiveness is verified in the frequency domain and the time domain. The results shed new light on the effects of the mount positions on the vibration energy transmission behaviors of the casing structure. The structural intensity method is a more advanced tool for solving vibration problems in engineering. Furthermore, it may provide some guidance for the vibration attenuation of the casing and the whole aero-engine.
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Tang, Hong, Guo Guang Chen, and Hui Zhu He. "An Aero-Thermo-Elasticity Method Applied on the Supersonic Aircraft Model." Applied Mechanics and Materials 215-216 (November 2012): 438–42. http://dx.doi.org/10.4028/www.scientific.net/amm.215-216.438.
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Coupling between the vibration frequencies and the unsteady aerodynamic will reduce the flutter speed and ride quality through the aerodynamic heat transfer. As the flight speed improved, the aeroelastic analysis has become an essential means of aircraft design. The method of aero-thermo-elastic (ATE) analysis is coupled with aircraft aeroelastic analysis and thermal deformation, and is more realistic reflection of the actual flight of the aircraft. In this paper, an ATE analysis of aircraft adopted by computational fluid dynamics/computational structural dynamics (CFD/CSD) methods, and compared with the traditional analysis, to provide analytical tools for the supersonic aircraft design.
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Jin, Zhu, Moli Chen, Gui-Huo Luo, and Lin Yue. "Analysis of the effect of squeeze film damper on the bending-torsional coupling vibration characteristics of dual-rotor system." 59th International Conference on Vibroengineering in Dubai, United Arab Emirates, October 22, 2022 45 (October 22, 2022): 1–7. http://dx.doi.org/10.21595/vp.2022.22902.
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The study of the vibration reduction characteristics of SFD to the bending-torsional coupled vibration of the dual-rotor system can provide support for the structural design of aero-engines. Based on the overall eccentric disc model, the bending-torsional coupling dynamic equation of the dual-rotor system is established in this paper. The amplitude and nonlinear periodic characteristics of the dual-rotor system are obtained by combining Newmark-β method and Newton-Raphson method. The results show that the vibration reduction effect of SFD on bending-torsional coupling vibration is closely related to the speed. The vibration reduction effect of SFD is weak at the first-order critical speed range and below, and reduces the torsional amplitude by 70 % at the second-order critical speed range and above. SFD kept the bending-torsional coupling vibration of the dual-rotor system stable in a stable 5-period motion state.
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Shi, Ao, Bo Lu, Dangguo Yang, Xiansheng Wang, Junqiang Wu, and Fangqi Zhou. "Study on model design and dynamic similitude relations of vibro-acoustic experiment for elastic cavity." Modern Physics Letters B 32, no. 12n13 (May 10, 2018): 1840047. http://dx.doi.org/10.1142/s021798491840047x.
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Coupling between aero-acoustic noise and structural vibration under high-speed open cavity flow-induced oscillation may bring about severe random vibration of the structure, and even cause structure to fatigue destruction, which threatens the flight safety. Carrying out the research on vibro-acoustic experiments of scaled down model is an effective means to clarify the effects of high-intensity noise of cavity on structural vibration. Therefore, in allusion to the vibro-acoustic experiments of cavity in wind tunnel, taking typical elastic cavity as the research object, dimensional analysis and finite element method were adopted to establish the similitude relations of structural inherent characteristics and dynamics for distorted model, and verifying the proposed similitude relations by means of experiments and numerical simulation. Research shows that, according to the analysis of scale-down model, the established similitude relations can accurately simulate the structural dynamic characteristics of actual model, which provides theoretic guidance for structural design and vibro-acoustic experiments of scaled down elastic cavity model.
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Aye, Moe Moe, and Uwe Ritschel. "Global Dynamic Response of a Medium-Sized Floating Offshore Wind Turbine with Stall Regulation." Energies 15, no. 1 (December 27, 2021): 166. http://dx.doi.org/10.3390/en15010166.
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In this paper, a two-bladed medium-sized floating wind turbine with variable speed and power regulation by stall is studied. For floating offshore wind turbines, the major challenges are related to the dynamical behavior of the system in response to combined wind and wave loading. Especially for smaller systems, the coupling of aerodynamic and wave forces may lead to large amplitude motions. Coupled aero-hydro-servo-elastic simulations are carried out in OpenFAST. The goal of the study is to investigate the global dynamic response of the hypothetical wind turbine with stall regulation. Stall regulation concept is proposed and the structural loads are computed and results are presented and discussed.
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Shi, Yu, Shuiting Ding, Peng Liu, Tian Qiu, Chuankai Liu, Changbo Qiu, and Dahai Ye. "Swirl Flow and Heat Transfer in a Rotor-Stator Cavity with Consideration of the Inlet Seal Thermal Deformation Effect." Aerospace 10, no. 2 (January 31, 2023): 134. http://dx.doi.org/10.3390/aerospace10020134.
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In the typical structure of a turboshaft aero-engine, the mass flow of the cooling air in the rotor-stator cavity is controlled by the inlet seal labyrinth. This study focused on the swirl flow and heat transfer characteristics in a rotor-stator cavity with considerations of the inlet seal thermal deformation effect. A numerical framework was established by integrating conjugate heat transfer (CHT) analysis and structural finite element method (FEM) analysis to clarify the two-way aero-thermo-elasto coupling interaction among elastic deformation, leakage flow, and heat transfer. Simulation results showed that the actual hot-running clearance was non-uniform along the axial direction due to the temperature gradient and inconsistent structural stiffness. Compared with the cold-built clearance (CC), the minimum tip clearance of the actual non-uniform hot-running clearance (ANHC) was reduced by 37–40%, which caused an increase of swirl ratio at the labyrinth outlet by 5.3–6.9%, a reduction of the Nusselt number by up to 69%. The nominal uniform hot-running clearance (NUHC) was defined as the average labyrinth tip clearance. The Nusselt number of the rotating disk under the ANHC was up to 81% smaller than that under the NUHC. Finally, a clearance compensation method was proposed to increase the coolant flow and decrease the metal temperature.
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Pei, Xi, Min Xu, and Dong Guo. "Aeroelastic-Acoustics Numerical Simulation Research." Applied Mechanics and Materials 226-228 (November 2012): 500–504. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.500.
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The generation of aerodynamic noise of aircraft in flight is due to dynamical system and aerodynamic .The response of aircraft subjected to High acoustic loads and aerodynamic loads can produce fatigue and damage. In this paper a new Aeroelastic- Acoustics which adds acoustic loads in aeroelastic is presented. The emphasis of the study is the discipline of displacement and load of the flexible structure under the unsteady aerodynamic, inertial, elastic and aero-acoustic. The CFD/CSD/CAA coupling is used to simulate rockets cabin. Sound generated by a rocker is predicted numerically from a Large Eddy simulation (LES) of unsteady flow field. The Lighthill acoustic analogy is used to model the propagation of sound. The structural response of rocket cabin was given. The boundary-layer transition on the pressure side of the cabin is visualized, by plotting to better illustrate the essential interaction between fluctuating pressure and structure.CFD/CSD/CAA coupling compute method is validated in low and middle frequency.
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Wang, Tong, Yankai Wang, Meiru Liu, and Zhicai Zhong. "Stability Analysis of Rotor with a Spline Coupling." Journal of Physics: Conference Series 2252, no. 1 (April 1, 2022): 012001. http://dx.doi.org/10.1088/1742-6596/2252/1/012001.
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Abstract The spline coupling is widely used in aero-engines. Once the spline coupling fails, it will cause great damage to the engine. In this paper, the stability of a rotor with a spline coupling was studied. The internal damping instability model of the rotor with spline coupling is deduced, and the instability mechanism is explored. The stability boundary is analyzed by using the R-H criterion. The mechanism of rotor instability is analyzed by simulation. An experimental system of rotors with different structural parameters of spline coupling was built. The influence of the positioning surface clearance on the stability was analyzed. The modeling results show that the internal friction of the spline coupling will introduce additional damping and anti-symmetrical cross stiffness to the rotor, the additional damping will reduce the vibration response, and the anti-symmetrical cross stiffness will cause the rotor to become unstable. The simulation and experimental results show that the rotor system will not be unstable when the two positioning surfaces of the spline coupling are in an interference fit. When one of the positioning surfaces is a clearance fit and the other is an interference fit, the internal friction will cause the rotor to become unstable. The instability threshold speed is higher than the first-order critical speed. At the same time, due to the additional damping introduced by the sleeve tooth structure, there will be a transition stage of instability. At this time, the rotor will vibrate with sub-harmonic components, but the vibration amplitude of the rotor will decrease. When the two positioning surfaces are clearance fit, the rotor is unstable and the amplitude increases suddenly. The obtained instability characteristics of the rotor with spline coupling have important value for the instability fault diagnosis, and provide help for the stability control.
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Wang, Tong, Yankai Wang, Meiru Liu, and Zhicai Zhong. "Stability Analysis of Rotor with a Spline Coupling." Journal of Physics: Conference Series 2252, no. 1 (April 1, 2022): 012001. http://dx.doi.org/10.1088/1742-6596/2252/1/012001.
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Abstract The spline coupling is widely used in aero-engines. Once the spline coupling fails, it will cause great damage to the engine. In this paper, the stability of a rotor with a spline coupling was studied. The internal damping instability model of the rotor with spline coupling is deduced, and the instability mechanism is explored. The stability boundary is analyzed by using the R-H criterion. The mechanism of rotor instability is analyzed by simulation. An experimental system of rotors with different structural parameters of spline coupling was built. The influence of the positioning surface clearance on the stability was analyzed. The modeling results show that the internal friction of the spline coupling will introduce additional damping and anti-symmetrical cross stiffness to the rotor, the additional damping will reduce the vibration response, and the anti-symmetrical cross stiffness will cause the rotor to become unstable. The simulation and experimental results show that the rotor system will not be unstable when the two positioning surfaces of the spline coupling are in an interference fit. When one of the positioning surfaces is a clearance fit and the other is an interference fit, the internal friction will cause the rotor to become unstable. The instability threshold speed is higher than the first-order critical speed. At the same time, due to the additional damping introduced by the sleeve tooth structure, there will be a transition stage of instability. At this time, the rotor will vibrate with sub-harmonic components, but the vibration amplitude of the rotor will decrease. When the two positioning surfaces are clearance fit, the rotor is unstable and the amplitude increases suddenly. The obtained instability characteristics of the rotor with spline coupling have important value for the instability fault diagnosis, and provide help for the stability control.
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Hussain, R., H. Yue, and L. Recalde-Camacho. "Model predictive control of wind turbine with aero-elastically tailored blades." Journal of Physics: Conference Series 2265, no. 3 (May 1, 2022): 032084. http://dx.doi.org/10.1088/1742-6596/2265/3/032084.
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Abstract The use of aero-elastically tailored blades (ATB) for large wind turbines has shown the benefit of mitigating blade loads, in a passive adaptive manner, with the design of bend-twist coupling (BTC) along the blades. The BTC design makes the blades torsionally flexible and capable of adapting to different wind speeds. However, such increased flexibility makes the turbine modeling computationally demanding and the real-time controller design more challenging. In this work, to include the ATB effect into the turbine model for control, a twofold modeling for ATB characteristics is proposed. First a static BTC distribution is added to the turbine aerodynamics to account for the blade’s pre-bend-twist design, next a second-order transfer function is introduced to approximate the blade structural dynamic response to wind speed variations. The nonlinear model of the whole ATB wind turbine is built up in Simulink, linearized and discretized into a state-space form. A model predictive controller (MPC) is developed with the actuator constraints considered. Simulation studies are conducted on a 5MW ATB wind turbine at a selected above-rated wind speed. The use of the simplified model for control is assessed and the performance of MPC is compared to the gain-scheduling baseline controller.
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Sun, Junfeng, Meihong Liu, Zhen Xu, Taohong Liao, Xiangping Hu, Yuxian Li, and Juan Wang. "Coupled Fluid–Solid Numerical Simulation for Flow Field Characteristics and Supporting Performance of Flexible Support Cylindrical Gas Film Seal." Aerospace 8, no. 4 (April 2, 2021): 97. http://dx.doi.org/10.3390/aerospace8040097.
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A new type of cylindrical gas film seal (CGFS) with a flexible support is proposed according to the working characteristics of the fluid dynamic seal in high-rotational-speed fluid machinery, such as aero-engines and centrifuges. Compared with the CGFS without a flexible support, the CGFS with flexible support presents stronger radial floating characteristics since it absorbs vibration and reduces thermal deformation of the rotor system. Combined with the structural characteristics of a film seal, an analytical model of CGFS with a flexible wave foil is established. Based on the fluid-structure coupling analysis method, the three-dimensional flow field of a straight-groove CGFS model is simulated to study the effects of operating and structural parameters on the steady-state characteristics and the effects of gas film thickness, eccentricity, and the number of wave foils on the equivalent stress of the flexible support. Simulation results show that the film stiffness increases significantly when the depth of groove increases. When the gas film thickness increases, the average equivalent stress of the flexible support first decreases and then stabilizes. Furthermore, the number of wave foils affects the average foils thickness. Therefore, when selecting the number of wave foils, the support stiffness and buffer capacity should be considered simultaneously.
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Serafeim, G., D. Manolas, V. Riziotis, and P. Chaviaropoulos. "Multidisciplinary aeroelastic optimization of a 10MW-scale wind turbine rotor targeting to reduced LCoE." Journal of Physics: Conference Series 2265, no. 4 (May 1, 2022): 042051. http://dx.doi.org/10.1088/1742-6596/2265/4/042051.
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Abstract In the present paper, multidisciplinary optimization (MDAO) is applied with the aim to reduce the levelized cost of energy (LCoE) of the DTU-10MW Reference Wind Turbine (RWT) rotor. As application paradigm, the widely applied in the literature passive load control method of Bend Twist Coupling (BTC) is considered. The integrated optimization framework combines in a common loop, rotor aerodynamic and full wind turbine structural elasto-dynamic analyses, aiming at determining the optimum rotor diameter, the planform of the blade in terms of twist and chord distributions, the offset ply angle for BTC and the inner structure of the blade with cost function directly the LCoE. It is based on an in-house servo-aero-elastic analysis tool for determining the ultimate loads along the span of the blades and the power yield, whereas a cross-sectional analysis tool is employed for acquiring structural properties of the modified blade and stresses distributions over the blade sections. A cost model of the overall wind turbine is implemented by combining existing in the literature models and open data. The new rotor design is found to have a reduced LCoE by 0.71% and to produce 2.4% higher energy annually due to its increased by 3.7% diameter.
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Ovchinnikov, V. V., and Yu V. Petrov. "Study of running engines inertial and gyroscopic properties influence on the dynamic system engine – pylon – wing structural capabilities." Civil Aviation High Technologies 23, no. 3 (July 3, 2020): 63–72. http://dx.doi.org/10.26467/2079-0619-2020-23-3-63-72.
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A modern large-sized aircraft dynamic properties analysis, determined by the specificity of its layout scheme, demonstrates that the engines on under the wing elastic pylons lightly damped oscillations cause a number of undesirable phenomena, including intense accumulation of fatigue damage of the pylon-to-the-wing attachment, in fact in the area of engine installation in the pylon and the wing. The results of theoretical and experimental research show that with some engine attachment to the pylon structural modification it becomes possible to use the engines inertial and gyroscopic properties to absorb these oscillations. In this case, the motor tones damping coefficients increase by an order of magnitude or even more, so the gyroscopic coupling of elastic vibration tones is realized. With the rational choice of the additional parameters of elastic and dissipative bonds in the engine attachments it is possible to affect the aircraft wing and engines aero elastic vibrations effectively, which has a significant effect on the aircraft elements structural capabilities. A mathematical model of aero elasticity (MMAE) with respect to the kinetic moment of the engine rotors and specially designed units for attaching the engines to the pylons was developed in order to study the influence and the selection of rational elastic-dissipative parameters of the pylons-under-the-wing aircraft engine mounts. The method of predetermined basic forms is used for the aircraft with running engines on the pylons MMAE synthesis. The given forms are considered as the aircraft basic structure forms natural vibrations in the void. This work treats the engine nacelle and the rotor as absolutely rigid bodies, the elasticity of the rotor to the nacelle attachment is neglected. The pylon is modeled by an elastic beam, and the elastic and dissipative properties of the pylon-to-the-wing and the engine-to-the-pylon attachments are correspondingly by elastic-dissipative bonds. Schematic diagrams of the engine to the pylon attachments are proposed. The results of the study devoted to the influence of the proposed attachment points modifications on the load and integral strength characteristics of the main structural elements of the engine – pylon – wing dynamic system on the example of an An-124 aircraft are presented. The practical implementation of the proposed solutions aimed to reduce the level of fatigue damage to structural elements of the aircraft feasibility is proved.
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Chen, Peng, Jiahao Chen, and Zhiqiang Hu. "Review of Experimental-Numerical Methodologies and Challenges for Floating Offshore Wind Turbines." Journal of Marine Science and Application 19, no. 3 (September 2020): 339–61. http://dx.doi.org/10.1007/s11804-020-00165-z.
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Abstract Due to the dissimilar scaling issues, the conventional experimental method of FOWTs can hardly be used directly to validate the full-scale global dynamic responses accurately. Therefore, it is of absolute necessity to find a more accurate, economic and efficient approach, which can be utilized to predict the full-scale global dynamic responses of FOWTs. In this paper, a literature review of experimental-numerical methodologies and challenges for FOWTs is made. Several key challenges in the conventional basin experiment issues are discussed, including scaling issues; coupling effects between aero-hydro and structural dynamic responses; blade pitch control strategies; experimental facilities and calibration methods. Several basin experiments, industrial projects and numerical codes are summarized to demonstrate the progress of hybrid experimental methods. Besides, time delay in hardware-in-the-loop challenges is concluded to emphasize their significant role in real-time hybrid approaches. It is of great use to comprehend these methodologies and challenges, which can help some future researchers to make a footstone for proposing a more efficient and functional hybrid basin experimental and numerical method.
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Delavenne, M., E. Benard, S. Defoort, C. David, N. Fabbiane, J. S. Schotte, G. Arnoult, and G. Carrier. "Multi-fidelity weight analyses for high aspect ratio strut-braced wings preliminary design." IOP Conference Series: Materials Science and Engineering 1226, no. 1 (February 1, 2022): 012009. http://dx.doi.org/10.1088/1757-899x/1226/1/012009.
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Abstract In the wake of ”flygskam” movement that emerged in Sweden a couple of years ago many voices recently raised denounce the environmental footprint of aviation. Even if the real impact of the sector could appear rather limited the critics reveal the necessity to propose cleaner aircraft to both meet public expectations and environmental goals. Because the classical wing-tube configuration seems to have reached its limits, disruptive designs must be considered. Among the perspectives to reduce emissions, high-aspect ratio wings represent a promising path to be explored within the European CleanSky2 project U-HARWARD. Indeed, substantial diminution of induced drag are expected from those new configurations resulting in fewer fuel consumption. To achieve high-aspect ratio without compromising the structural weight strut can be introduced. They allow for an alleviation of the bending moment at the wing root and therefore lighter structures. However, the consideration of those new wing configuration at early design stages is not straightforward and new methods have to be introduced. In this paper, we present three different fidelity approaches to tackle with (ultra) high-aspect ratio strut-braced wings sizing and weight estimation in preliminary design context. Already existing analytical formulations for the wings are extended, intermediate fidelity aero-structural coupling has been developed and high-fidelity structural representation are considered. Depending on the maturity of the concept these methods could be used to explore the design space, to refine the optimum or to analyse the final concept. Validation with respect to reference configurations is provided. Then the methods are applied to the analysis of strut-braced wings.
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Esbati Lavasani, Reza, and Shahrokh Shams. "A New Dynamic Stall Approach for Investigating Bifurcation and Chaos in Aeroelastic Response of a Blade Section with Flap Free-Play Section." International Journal of Bifurcation and Chaos 30, no. 14 (November 2020): 2050200. http://dx.doi.org/10.1142/s0218127420502004.
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This paper investigates the effects of the unsteady nonlinear aerodynamic, plunge/pitch cubic nonlinearities, flap free-play nonlinearity, and coupled nonlinear aeroelasticity on the dynamics of the three-dimensional blade section. The dynamic stall model is developed based on the unsteady Wagner aerodynamics. Coupling the developed nonlinear aerodynamic model and nonlinear elasticity model results in the nonlinear aeroelastic model. The nonlinear aeroelastic equation of motion is converted into a state-space form. The resulting nonlinear state-space equation of motion is simulated by a standard Runge–Kutta algorithm in MATLAB. The proposed model is validated against test data of distinct two- and three-degrees-of-freedom studies and is compared to the ONERA model. Bifurcation diagrams show that there is distinct airspeed, in which the system experiences limit cycle oscillations (LCOs) or chaos. Both hysteresis air loads and structural nonlinearity make the system unstable at airspeed less than linear flutter speed. The nonlinearity of the structure causes supercritical pitchfork bifurcation. Elastic-aerodynamic nonlinearity interaction causes sub-supercritical bifurcation at the lower airspeed and chaotic motion at a higher airspeed. Furthermore, the effects of the initial condition on the response of the nonlinear aero-servo-elastic system are investigated by the Lyapunov exponent method.
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Fang, Li Cheng, and Shun Ming Li. "A Review of the Research on Aeroelasticity in Aero Turbomachinery." Advanced Materials Research 651 (January 2013): 694–700. http://dx.doi.org/10.4028/www.scientific.net/amr.651.694.
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Aeroelasticity in the form of blade flutter is a major concern for designers in the field of turbomachinery. This paper presents a review of the research and development on blade flutter modeling, including the unsteady aerodynamic model, the structural model and flutter prediction methods. Based on the presentation of these models, the fundamental mechanism and effects of different treatments are discussed. At the end of paper, some deficiencies in the research of flutter and difficulties in modeling fluid-solid coupling effects are pointed out, to which attention should be paid in future.
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Bortolotti, Pietro, Carlo L. Bottasso, and Alessandro Croce. "Combined preliminary–detailed design of wind turbines." Wind Energy Science 1, no. 1 (May 30, 2016): 71–88. http://dx.doi.org/10.5194/wes-1-71-2016.
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Abstract. This paper is concerned with the holistic optimization of wind turbines. A multi-disciplinary optimization procedure is presented that marries the overall sizing of the machine in terms of rotor diameter and tower height (often termed “preliminary design”) with the detailed sizing of its aerodynamic and structural components. The proposed combined preliminary–detailed approach sizes the overall machine while taking into full account the subtle and complicated couplings that arise due to the mutual effects of aerodynamic and structural choices. Since controls play a central role in dictating performance and loads, control laws are also updated accordingly during optimization. As part of the approach, rotor and tower are sized simultaneously, even in this case capturing the mutual effects of one component over the other due to the tip clearance constraint. The procedure, here driven by detailed models of the cost of energy, results in a complete aero-structural design of the machine, including its associated control laws. The proposed methods are tested on the redesign of two wind turbines, a 2.2 MW onshore machine and a large 10 MW offshore one. In both cases, the optimization leads to significant changes with respect to the initial baseline configurations, with noticeable reductions in the cost of energy. The novel procedures are also exercised on the design of low-induction rotors for both considered wind turbines, showing that they are typically not competitive with conventional high-efficiency rotors.
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Zhang, Hongxian, Liangpei Huang, Xuejun Li, Lingli Jiang, Dalian Yang, Fanyu Zhang, and Jingjing Miao. "Spectrum Analysis of a Coaxial Dual-Rotor System with Coupling Misalignment." Shock and Vibration 2020 (July 10, 2020): 1–19. http://dx.doi.org/10.1155/2020/5856341.
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The finite element model of a dual-rotor system was established by Timoshenko beam element. The dual-rotor system is a coaxial rotor whose supporting structure is similar to that of an aero-engine rotor system. The inner rotor is supported by three bearings, which makes it a redundantly supported rotor. The outer rotor connects the inner rotor by an intershaft bearing. The spectrum characteristics of the dual-rotor system under unbalanced excitation and misalignment excitation were analysed in order to study the influence of coupling misalignment of the inner rotor on the spectral characteristics of the rotor system. The results indicate that the vibration caused by the misaligned coupling of the inner rotor will be transmitted to the outer rotor through the intershaft bearing. Multiple harmonic frequency components, mainly 1x and 2x, will be excited by the coupling misalignment. The amplitudes of all harmonic frequencies increase with the misalignment in both the inner and outer rotors. The vibration level of the outer rotor affected by the misalignment is lower than that of the inner rotor because it is far from the misaligned coupling. Harmonic resonance occurs when any harmonic frequencies of the misalignment response coincide with a natural frequency of the system. In order to verify the theoretical model, experiments are performed on a test rig. Both the experimental and simulation results are in good accordance with each other.
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Hua, Xugang, Qingshen Meng, Bei Chen, and Zili Zhang. "Structural damping sensitivity affecting the flutter performance of a 10-MW offshore wind turbine." Advances in Structural Engineering 23, no. 14 (June 15, 2020): 3037–47. http://dx.doi.org/10.1177/1369433220927260.
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Classical flutter of wind turbine blades is one of the most destructive instability phenomena of wind turbines especially for several-MW-scale turbines. In the present work, flutter performance of the DTU 10-MW offshore wind turbine is investigated using a 907-degree-of-freedom aero-hydro-servo-elastic wind turbine model. This model involves the couplings between tower, blades and drivetrain vibrations. Furthermore, the three-dimensional aerodynamic effects on wind turbine blade tip have also been considered through the blade element momentum theory with Bak’s stall delay model and Shen’s tip loss correction model. Numerical simulations have been carried out using data calibrated to the referential DTU 10-MW offshore wind turbine. Comparison of the aeroelastic responses between the onshore and offshore wind turbines is made. Effect of structural damping on the flutter speed of this 10-MW offshore wind turbine is investigated. Results show that the damping in the torsional mode has predominant impact on the flutter limits in comparison with that in the bending mode. Furthermore, for shallow water offshore wind turbines, hydrodynamic loads have small effects on its aeroelastic response.
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Li, Jinghui, Wei Shi, Lixian Zhang, Constantine Michailides, and Xin Li. "Wind–Wave Coupling Effect on the Dynamic Response of a Combined Wind–Wave Energy Converter." Journal of Marine Science and Engineering 9, no. 10 (October 9, 2021): 1101. http://dx.doi.org/10.3390/jmse9101101.
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There is a huge energy demand from offshore renewable energy resources. To maximize the use of various renewable energy sources, a combined floating energy system consisting of different types of energy devices is an ideal option to reduce the levelized cost of energy (LCOE) by sharing the infrastructure of the platform and enhancing the power production capacity. This study proposed a combined concept of energy systems by combing a heave-type wave energy converter (WEC) with a semisubmersible floating wind turbine. In order to investigate the power performance and dynamic response of the combined concept, coupled aero-hydro-servo-elastic analysis was carried out using the open-source code F2A, which is based on the coupling of the FAST and AQWA tools by integrating all the possible environmental loadings (e.g., aerodynamic, hydrodynamic). Numerical results obtained by AQWA are used to verify the accuracy of the coupled model in F2A in predicting dynamic responses of the combined system. The main hydrodynamic characteristics of the combined system under typical operational conditions were examined, and the calculated responses (motions, mooring line tension and produced wave power) are discussed. Additionally, the effect of aerodynamic damping on the dynamic response of the combined system was examined and presented. Moreover, a second fully coupled analysis model was developed, and its response predictions were compared with the predictions of the model developed with F2A in order for the differences of the calculated responses resulted by the different modeling techniques to be discussed and explained. Finally, the survivability of the combined concept has been examined for different possible proposed survival modes.
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Gong, Miao, Shijie Dai, Tao Wang, and Liwen Wang. "Modeling of additive height and numerical analysis of cooling parameters for aero blade remanufacturing." Mechanical Sciences 12, no. 2 (August 24, 2021): 803–18. http://dx.doi.org/10.5194/ms-12-803-2021.
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Abstract. Additive remanufacturing height and matching cooling parameters are the key factors affecting blade repair quality. First, the mathematical model of the single additive remanufacturing repair height and wire-feeding speed was established, the solution method was proposed and the numerical solution was obtained, and the validity of the model was verified by experiments. Then, based on the calculation results of a single additive remanufacturing repair, the geometric morphology of the cross section under double additive remanufacturing repair was analyzed, and the mathematical model was established. Second, based on the optimal parameters obtained by numerical analysis and the mathematical model, the fluid structure coupling heat transfer model of “blade fixture” for base channel cooling was established. The cooling effect of the typical section under different initial temperatures and different flow rates was calculated, and the coupled heat transfer in the process of blade remanufacturing was explained by the mechanism. Third, through the comparative analysis of the cooling effect, optimal cooling parameters of double additive remanufacturing repair were obtained, and the model of coupled heat flow was verified by experiment. The results showed that the mathematical model of additive remanufacturing height is effective for studying the thermal cycle and cooling effect of welding, and the cooling parameters obtained by numerical analysis can effectively guarantee the quality of double additive remanufacturing of blade repair.
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Zhangaskanov, Dinmukhamed, Sagidolla Batay, Bagdaulet Kamalov, Yong Zhao, Xiaohui Su, and Eddie Yin Kwee Ng. "High-Fidelity 2-Way FSI Simulation of a Wind Turbine Using Fully Structured Multiblock Meshes in OpenFoam for Accurate Aero-Elastic Analysis." Fluids 7, no. 5 (May 11, 2022): 169. http://dx.doi.org/10.3390/fluids7050169.
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With increased interest in renewable energy, the power capacity of wind turbines is constantly increasing, which leads to increased rotor sizes. With ever larger rotor diameters, the complex and non-linear fluid-structure interaction (FSI) effects on wind turbine aerodynamic performances become significant, which can be fully studied using hi-fidelity 2-way FSI simulation. In this study, a two-way FSI model is developed and implemented in Openfoam to investigate the FSI effects on the NREL Phase VI wind turbine. The fully structured multiblock (MB) mesh method is used for the fluid and solid domains to achieve good accuracy. A coupling method based on the ALE is developed to ensure rotation and deformation can happen simultaneously and smoothly. The simulation results show that hi-fidelity CFD (Computational Fluid Dynamics) and CSD (Computational Structural Dynamics) -based 2-way FSI simulation provides high accurate results for wind turbine simulation and multi-disciplinary design optimization (MDO).
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Pan, Fang, Hou Yongjun, Dai Liming, and Du Mingjun. "Theoretical Study of Synchronous Behavior in a Dual-Pendulum-Rotor System." Shock and Vibration 2018 (July 9, 2018): 1–13. http://dx.doi.org/10.1155/2018/9824631.
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A dual-pendulum-rotor system widely appears in aero-power plant, mining screening machines, parallel robots, and the like of the other rotation equipment. Unfortunately, the synchronous behavior related to the dual-pendulum-rotor system is less reported. Based on the special backgrounds, a simplified mechanical model of the dual-pendulum-rotor system is proposed in the paper, and the intrinsic mechanisms of synchronous phenomenon in the system are further revealed with employing the Poincaré method. The research results show that the spring stiffness, the installation angular of the motor, and rotation direction of the rotors have a large influence on the existence and stability of the synchronization state in the coupling system, and the mass ratios of the system are irrelevant to the synchronous state of the system. It should be noted that to ensure the implementation of the synchronization of the system, the values of the parameters of the system should be far away to the two “critical points”.
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Bai, Yuguang, Wei Qian, Xiangyan Chen, and Taojun Lu. "Experimental and numerical study of dynamic characteristic of a complex all-movable rudder system." Journal of Low Frequency Noise, Vibration and Active Control 37, no. 3 (October 8, 2017): 654–64. http://dx.doi.org/10.1177/1461348417733930.
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Modal analysis and flutter computation of a complex tail cabin system including six all-movable rudders for hypersonic flight vehicle was studied in this paper. Recently, some complex all-movable rudder system has been applied to hypersonic flight vehicle. Many investigations were taken to analyse a single all-movable rudder, such as modal analysis, flutter analysis, aero-heating analysis, etc. But most of existing investigations emphasized on single rudder. In this paper, a complex tail cabin system including six all-movable rudders from the X-51A vehicle was investigated. Modal analysis was presented based on accurate finite element modelling and bending and twisting modes of the structure were computed. Ground vibration test was provided to confirm the accuracy of computation. Then flutter characteristic of this complex system was analysed based on doublet lattice method. With flight Mach number 3 and 4, flutter analysis relating to both symmetric mode and antisymmetric mode was presented. It can be found from the presented results of flutter analysis that there were obvious and non-negligible coupling vibration effects among rudders in such a complex rudder system. So flutter characteristic of hypersonic flight vehicle should be analysed based on the whole system modelling including all of rudders. This analysis process can play a significant role for the design and flight of hypersonic vehicle.
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Abate, Giada, Johannes Riemenschneider, and Alexander Hergt. "Aero-Structural Coupling Strategy for a Morphing Blade Cascade Study." Journal of Turbomachinery 144, no. 6 (January 28, 2022). http://dx.doi.org/10.1115/1.4053174.
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Abstract The coupling of aerodynamics and structural mechanics is an important step in the design process of aeronautical devices with morphing parts. In this article, a 2D–3D coupling approach is developed to study a morphing blade cascade. Two shape memory alloy actuators are placed on the upper and lower sides of the blade to make possible the change in shape of the leading edge. In the present study, a preliminary design study is conducted by considering a two-dimensional computational fluid dynamics (CFD) analysis of an airfoil cascade coupled with a three-dimensional structural analysis of the whole 3D blade. A methodology is developed to match 2D and 3D meshes such that the aerodynamic loads can be easily transferred to the structural analysis. From there, the deformed blade geometry due to both aerodynamic loads and actuator work can be transferred back to the CFD solver, and the iterative aero-structural coupling loop can be repeated until convergence. The aero-structural coupling strategy developed in this study is also applied to a blade cascade study aiming to improve its performance by morphing the leading-edge of the blade. The results of this application show that by morphing the leading-edge blade of only few millimeters (less than 2 mm), it is possible to achieve a relevant performance improvement in terms of total pressure loss coefficient decrease of about 53% considering off-design conditions.
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Ma, Yingqun, Qingjun Zhao, Kai Zhang, Meng Xu, and Wei Zhao. "Analysis of Instantaneous Vibrational Energy Flow for an Aero-Engine Dual-Rotor–Support–Casing Coupling System." Journal of Engineering for Gas Turbines and Power 142, no. 5 (April 29, 2020). http://dx.doi.org/10.1115/1.4046418.
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Abstract The aero-engine casing is a key component for carrying loads. With the purpose of improving the thrust-weight ratio of the aero-engine, the casing is required to be designed to be as thin as possible. Therefore, the vibration of aero-engine's rotor, support, and casing will be easily coupled causing the whole engine's vibration to be more serious. Considering the structural vibration propagation is essentially the vibration energy transmission, the structural intensity (SI) method is popular and widely used to investigate the transmission phenomena of vibration energy in vibrating structures. This method combines forces with velocities to quantify the vibrational energy flow (VEF) transmitted in the structures by its directions and magnitude. Therefore, the SI fields are quantified by the developed computation system which combines the finite element design language and the in-house code. And a model of dual-rotor–support–casing coupling system subjected to the unbalanced forces of the rotors is established in this paper. The scalar and vector diagrams of instantaneous SI fields are visualized to show the main vibration energy transmission paths among these three parts. Moreover, the relationship between the SI and the mechanical energy is derived from the kinetic equation. According to this relationship, the phenomenon that the vibration energy and the strain energy are always converted to each other in the middle part of the rotor shaft with the first-order bending mode is discussed, which reveals the cause of the first-order bending mode of the rotor from a microscopic point of view.
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Marten, David, Matthew Lennie, George Pechlivanoglou, Christian Oliver Paschereit, Alessandro Bianchini, Giovanni Ferrara, and Lorenzo Ferrari. "Benchmark of a Novel Aero-Elastic Simulation Code for Small Scale VAWT Analysis." Journal of Engineering for Gas Turbines and Power 141, no. 4 (November 28, 2018). http://dx.doi.org/10.1115/1.4041519.
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After almost 20 years of absence from research agendas, interest in the vertical axis wind turbine (VAWT) technology is presently increasing again, after the research stalled in the mid 90's in favor of horizontal axis wind turbines (HAWTs). However, due to the lack of research in past years, there are a significantly lower number of design and certification tools available, many of which are underdeveloped if compared to the corresponding tools for HAWTs. To partially fulfill this gap, a structural finite element analysis (FEA) model, based on the Open Source multiphysics library PROJECT::CHRONO, was recently integrated with the lifting line free vortex wake (LLFVW) method inside the Open Source wind turbine simulation code QBlade and validated against numerical and experimental data of the SANDIA 34 m rotor. In this work, some details about the newly implemented nonlinear structural model and its coupling to the aerodynamic solver are first given. Then, in a continuous effort to assess its accuracy, the code capabilities were here tested on a small-scale, fast-spinning (up to 450 rpm) VAWT. The study turbine is a helix shaped, 1 kW Darrieus turbine, for which other numerical analyses were available from a previous study, including the results coming from both a one-dimensional beam element model and a more sophisticated shell element model. The resulting data represented an excellent basis for comparison and validation of the new aero-elastic coupling in QBlade. Based on the structural and aerodynamic data of the study turbine, an aero-elastic model was then constructed. A purely aerodynamic comparison to experimental data and a blade element momentum (BEM) simulation represented the benchmark for QBlade aerodynamic performance. Then, a purely structural analysis was carried out and compared to the numerical results from the former. After the code validation, an aero-elastically coupled simulation of a rotor self-start has been performed to demonstrate the capabilities of the newly developed model to predict the highly nonlinear transient aerodynamic and structural rotor response.
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Kuan, Lu, Hui Cheng, Zhang Wentao, Zhang Haopeng, Kaifu Zhang, and Chao Fu. "Nonlinear dynamic behaviors of a dual-rotor bearing system with coupling misalignment and rubbing faults." Measurement Science and Technology, September 29, 2022. http://dx.doi.org/10.1088/1361-6501/ac9639.
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Abstract Taking the dual rotor system in the aero-engine as the research object, the vibration behaviors of the dual rotor bearing system with fault-free, misalignment fault, rub impact fault and misalignment rub impact coupling fault are studied, respectively. Firstly, the three-dimensional model of the dual rotor bearing system is established, and then the first six modes and critical speeds of the dual rotor bearing system are obtained by the finite element method. Then, the dynamic equations of the dual rotor bearing system with fault-free, misalignment fault, rub-impact fault and misalignment rub-impact coupling fault are derived based on the Lagrange method. The Runge-Kutta method is used to solve the dynamic equation, and the nonlinear dynamic response of the system is obtained. The vibration behaviors of the dual rotor system with misalignment fault, rub-impact fault and misalignment rub impact coupling fault are analyzed and discussed through the time history, phase diagram, and frequency spectrum of the rotor. The vibration behaviors of the first six modes of the dual rotor system with fault-free, misalignment fault, rub-impact fault and misalignment rub-impact coupling fault are analyzed, respectively. The results can provide theoretical guidance for structural optimization design of the aero-engine rotor system and the prior decision information for misalignment and rub-impact coupling fault diagnosis.
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Antona, Ruben, Roque Corral, and Juan M. Gallardo. "Effect of the Structural Coupling on the Flutter Onset of a Sector of Low-Pressure Turbine Vanes." Journal of Turbomachinery 134, no. 5 (May 8, 2012). http://dx.doi.org/10.1115/1.4003837.
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The effect of the structural coupling in the aeroelastic stability of a packet of low-pressure turbine vanes is studied in detail. The dynamics of a 3D sector vane is reduced to that of a simplified mass-spring model to enhance the understanding of its dynamics and to perform sensitivity studies. It is concluded that the dynamics of the simplified model retains the basic features of the finite element three-dimensional model. A linear fully coupled analysis in the frequency domain of the 3D vane sector has been conducted. It is concluded that the small structural coupling provided by the casing and the inter-stage seal is essential to explain the experimental evidences. It is shown that the use of fully coupled aero/structural methods is necessary to retain the mode interaction that takes place in this type of configurations.
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liu, bo, Yang Yu, Feng Xia, and Yuanxin Li. "Design of a Novel Fiber Grating Acoustic Emission Sensor based on Coupling Cone Structure." Measurement Science and Technology, June 16, 2022. http://dx.doi.org/10.1088/1361-6501/ac79a2.
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Abstract A fiber Bragg grating (FBG) acoustic emission (AE) sensor based on coupling cone structure, which is flexible and reusable is proposed in this thesis, and the sensor is fabricated by additive manufacturing (AM) technology. The numerical modelling of the coupling cone structure was performed using finite element analysis (FEA). The influence of the coupling cone angle and material on the acoustic emission detection performance was studied. The main parameters of the coupling cone structure are determined. The acoustic emission detection of material tensile tests was studied by edge-filter-demodulation of spectrum technology. The experimental results demonstrated that the coupling cone FBG acoustic emission (Cone-FBG-AE) sensor has advantages of high sensitivity, flexibility and adjustable positioning, and can be reused. It realizes real-time monitoring of AE signals in the tensile process of the specimen, which is consistent with the effect of the resonant AE sensor. The Cone-FBG-AE sensor has great application value in the fields of health monitoring, such as aero-engines, microcracks of structural defects.
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Huan, Caiyun, Dongzhe Lu, Shengxiao Zhao, Wenhua Wang, Jin Shang, Xin Li, and Qingquan Liu. "Experimental Study of Ultra-Large Jacket Offshore Wind Turbine under Different Operational States Based on Joint Aero-Hydro-Structural Elastic Similarities." Frontiers in Marine Science 9 (July 26, 2022). http://dx.doi.org/10.3389/fmars.2022.915591.
Full textAbstract:
The jacket substructure is generalized for offshore wind farms in the southeastern offshore regions of China. The dynamic characteristics and coupling mechanisms of jacket offshore wind turbines (OWTs) have been extensively investigated using numerical simulation tools. However, limited dynamic model tests have been designed and performed for such types of OWTs. Therefore, the coupling mechanisms of jacket OWTs that are determined using numerical methods require further validation based on experimental tests. Accordingly, an integrated scaled jacket OWT physical test model is designed in this study. It consists of a scaled rotor nacelle assembly (RNA) and support structure model. For the scaled RNA model, a redesigned blade model is adopted to ensure the similarity of the aerodynamic thrust loads without modifying the scaled test winds. Auxiliary scaled drivetrain and blade pitch control system models are designed to simulate the operational states of a practical OWT. The scaled model of the OWT support structure is fabricated on the basis of the joint hydro-structural elastic similarities. A sensor arrangement involving a three-component load cell and acceleration sensors is used to record the OWT thrust loads and model motions, respectively. Then, dynamic model tests under typical scaled wind fields are implemented. Furthermore, the coupling mechanisms of the OWT model under various test winds are investigated using the wavelet packet method, and the influences of inflow winds, operational states, and mechanical strategies are introduced.
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"STRUCTURAL DESIGN AND ANALYSIS OF MAIN AERO CRAFT STRUCTURE AND COMPARISON OF DIFFERENT MATERIALS IN DIFFERENT CONDITIONS." International Journal For Innovative Engineering and Management Research, December 4, 2020, 54–60. http://dx.doi.org/10.48047/ijiemr/v09/i12/10.
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The project deals with the structural design and analysis of Main Aero craft structure (Skin, Floor mounting, Support Lugs) for assembling of electronic packages in a flight vehicle section. The flight vehicle consists of various sections assembled to form an integrated vehicle. Different types of electronic packages to meet the requirements are assembled in different flight vehicle sections based on the flight vehicle configuration. One such type of flight vehicle section needs to be assembled with different electronic packages. The packages have to be rigidly mounted on a mounting structure in the flight vehicle section. The high random vibration loads imparted on vehicle by the electronic packages during launch create an adverse design requirement that all hardware have a natural frequency greater than that of the vehicle, in order to avoid damage and failure due to dynamic coupling. Maximizing natural frequency is generally accomplished by creating as stiff and lightweight a design as possible. However, designing for the resultant high loads also requires a high strength intermediate structure for mounting the various components and subassemblies to the vehicle structure. These two opposing design requirements drive an optimization between a lightweight and high strength structure. The project comprises of design and analysis of the Aero craft structure (Skin, Floor mounting, Support Lugs). The Aero craft (Skin, Floor mounting, Support Lugs) structure has to be designed to withstand the loads generated by the electronic packages. It also includes the design of mounting plate and brackets to withstand the given loads using CAD and CAE tools. CATIA software is used for modeling the flight vehicle section, packages and the mounting plate with brackets. The mounting plate and brackets are imported to ANSYS software for structural analysis. The mounting plate with brackets is applied with specified loads in different flight conditions like Pitch, Yaw and Roll moments. A finite element model was created to manually iterate several aspects of the design, such as geometric characteristics like thicknesses and fillet radii, to analyze the effects on weight and stress and converge on a successful design. The project eludes in detail the methodology adopted for the analysis of Aero craft structures (Skin, Floor mounting, Support Lugs) for flight vehicles and comparison of different materials (Aluminium alloy (2025), Aluminum alloy (23435), Titanium Alloys (Ti4Al4Mo2Sn).
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Şener, Özgün, Touraj Farsadi, M. Ozan Gözcü, and Altan Kayran. "Evaluation of the Effect of Spar Cap Fiber Angle of Bending–Torsion Coupled Blades on the Aero-Structural Performance of Wind Turbines." Journal of Solar Energy Engineering 140, no. 4 (March 20, 2018). http://dx.doi.org/10.1115/1.4039350.
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This paper presents a comprehensive study of the evaluation of the effect of spar cap fiber orientation angle of composite blades with induced bending–torsion coupling (IBTC) on the aero-structural performance wind turbines. Aero-structural performance of wind turbines with IBTC blades is evaluated with the fatigue load mitigation in the whole wind turbine system, tower clearances, peak stresses in the blades, and power generation of wind turbines. For this purpose, a full E-glass/epoxy reference blade has been designed, following the inverse design methodology for a 5-MW wind turbine. An E-glass/epoxy blade with IBTC and novel, hybrid E-glass/carbon/epoxy blades with IBTC have been designed and aeroelastic time-marching multibody simulations of the 5-MW turbine systems, with the reference blade and the blades with IBTC, have been carried out using six different randomly generated turbulent wind profiles. Fatigue-equivalent loads (FELs) in the wind turbine have been determined as an average of the results obtained from the time response of six different simulations. The results reveal that certain hybrid blade designs with IBTC are more effective in fatigue load mitigation than the E-glass–epoxy blade with IBTC, and besides the fiber orientation angle, sectional properties of hybrid blades must be adjusted accordingly using proper number of carbon/epoxy layers in the sections of the blade with IBTC, in order to simultaneously reduce generator power losses and the FEL.
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Manolas, D. I., V. A. Riziotis, and S. G. Voutsinas. "Assessing the Importance of Geometric Nonlinear Effects in the Prediction of Wind Turbine Blade Loads." Journal of Computational and Nonlinear Dynamics 10, no. 4 (July 1, 2015). http://dx.doi.org/10.1115/1.4027684.
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As the size of commercial wind turbines increases, new blade designs become more flexible in order to comply with the requirement for reduced weights. In normal operation conditions, flexible blades undergo large bending deflections, which exceed 10% of their radius, while significant torsion angles toward the tip of the blade are obtained, which potentially affect performance and stability. In the present paper, the effects on the loads of a wind turbine from structural nonlinearities induced by large deflections of the blades are assessed, based on simulations carried out for the NREL 5 MW wind turbine. Two nonlinear beam models, a second order (2nd order) model and a multibody model that both account for geometric nonlinear structural effects, are compared to a first order beam (1st order) model. Deflections and loads produced by finite element method based aero-elastic simulations using these three models show that the bending–torsion coupling is the main nonlinear effect that drives differences on loads. The main effect on fatigue loads is the over 100% increase of the torsion moment, having obvious implications on the design of the pitch bearings. In addition, nonlinearity leads to a clear shift in the frequencies of the second edgewise modes.
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Ganine, Vladislav, John W. Chew, Nicholas Hills, Sulfi Noor Mohamed, and Matthew Miller. "Transient Aero-Thermo-Mechanical Multidimensional Analysis of a High Pressure Turbine Assembly Through a Square Cycle." Journal of Engineering for Gas Turbines and Power, January 4, 2021. http://dx.doi.org/10.1115/1.4049498.
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Abstract Better understanding and more accurate prediction of heat transfer and cooling flows in aero engine components in steady and transient operating regimes are essential to modern engine designs aiming at reduced cooling air consumption and improved engine efficiencies. This paper presents a simplified coupled transient analysis methodology that allows assessment of the aerothermal and thermomechanical responses of engine components together with cooling air mass flow, pressure and temperature distributions in an automatic fully integrated way. This is achieved by assembling a fluid network with contribution of components of different geometrical dimensions coupled to each other through dimensionally heterogeneous interfaces. More accurate local flow conditions, heat transfer and structural displacement are resolved on a smaller area of interest with multidimensional surface coupled CFD/FE codes. Contributions of the whole engine air-system are predicted with a faster mono dimensional flow network code. Matching conditions at the common interfaces are enforced at each time step exactly by employing an efficient iterative scheme. The coupled simulation is performed on an industrial high pressure turbine disk component run through a square cycle. Predictions are compared against the available experimental data. The paper proves the reliability and performance of the multidimensional coupling technique in a realistic industrial setting. The results underline the importance of including more physical details into transient thermal modelling of turbine engine components.
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Xiong, Gen, Dongzhe Lu, Zuxing Pan, Wenhua Wang, Xin Li, and Qingquan Liu. "Experimental study of dynamic characteristics of an ultra-large jacket offshore wind turbine under wind and wave loads using aero-hydro-structural elastic similarities." Frontiers in Energy Research 10 (January 6, 2023). http://dx.doi.org/10.3389/fenrg.2022.992854.
Full textAbstract:
Owing to the difficulties in the scaled rotor-nacelle assembly (RNA) and support structure design, and alleviation of small scaling effects, the limited dynamic model tests are conducted for the jacket offshore wind turbines (OWTs), which are extensively constructed in the offshore wind farms located in the depth of 40–50 m. To address this limitation, an integrated test method based on aero-hydro-structural elastic similarities is proposed in this study. It comprises a performance-scaled RNA model and a scaled support structure model. A redesigned blade model is adopted in the scaled RNA model to ensure the similarities of aerodynamic thrust loads without modifications of the scaled test winds. Moreover, auxiliary scaled drivetrain and blade pitch control are designed to simulate the operational states of a practical OWT. The scaled model of the OWT support structure is fabricated based on the joint hydro-structural elastic similarity, and the small scaling effects are mitigated by introducing sectional bending stiffness similarities. Subsequently, the dynamic model tests of an ultra-large jacket OWT under wind-only, wave-only, and combined wind and wave conditions are carried out. The accuracy of the fabricated OWT test model is validated based on the recorded responses, and the influence of the dominant frequencies on the dynamic responses of the OWT model is quantitatively evaluated using the wavelet packet-based energy analysis method. Further, the coupling mechanisms of the scaled OWT model under typical wind and wave loads are investigated, and the interactions between the environmental loads and OWT motions are proved.
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Seeley, Charles E., Christian Wakelam, Xuefeng Zhang, Douglas Hofer, and Wei-Min Ren. "Investigations of Flutter and Aerodynamic Damping of a Turbine Blade: Experimental Characterization." Journal of Turbomachinery 139, no. 8 (April 4, 2017). http://dx.doi.org/10.1115/1.4035840.
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Flutter is a self-excited and self-sustained aero-elastic instability, caused by the positive feedback between structural vibration and aerodynamic forces. A two-passage linear turbine cascade was designed, built, and tested to better understand the phenomena and collect data to validate numerical models. The cascade featured a center airfoil that had its pitch axis as a degree-of-freedom to enable coupling between the air flow and mechanical response in a controlled manner. The airfoil was designed to be excited about its pitch axis using an electromagnetic actuation system over a range of frequencies and amplitudes. The excitation force was measured with load cells, and the airfoil motion was measured with accelerometers. Extraordinary effort was taken to minimize the mechanical damping so that the damping effects of the airflow over the airfoil, that were of primary interest, would be observable. Assembling the cascade required specialized alignment procedures due to the tight clearances and large motion. The aerodynamic damping effects were determined by observing changes in the mechanical frequency response of the system. Detailed aerodynamic and mechanical measurements were conducted within a wide range of Mach numbers (Ma) from Ma = 0.10 to 1.20. Experimental results indicated that the aerodynamic damping increased from Ma = 0.10 to 0.65, dropped suddenly, and was then constant from Ma = 0.80 to 1.20. A flutter condition was identified in the interval between Ma = 0.65 and Ma = 0.80. The aerodynamic damping was also found to be independent of displacement amplitude within the tested range, giving credence to linear numerical approaches.
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Mayorca, María A., Damian M. Vogt, Torsten H. Fransson, and Hans Mårtensson. "A New Reduced Order Modeling for Stability and Forced Response Analysis of Aero-Coupled Blades Considering Various Mode Families." Journal of Turbomachinery 134, no. 5 (May 8, 2012). http://dx.doi.org/10.1115/1.4003830.
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This paper presents the description and application of a new method for stability and forced response analyses of aerodynamically coupled blades considering the interaction of various mode families. The method, here referred as multimode least square, considers the unsteady forces due to the blade motion at different modes shape families and calculates the aerodynamic matrixes by means of a least square (L2) approximations. This approach permits the prediction of mode families’ interaction with capabilities of structural, aerodynamic and force mistuning. A projection technique is implemented in order to reduce the computational domain. Application of the method on tuned and structural mistuned forced response and stability analyses is presented on a highly loaded transonic compressor blade. When considering structural mistuning the forced response amplitude magnification is highly affected by the change in aerodynamic damping due to mistuning. Analyses of structural mistuning without aerodynamic coupling might result in over-estimated or under-estimated response when the source of damping is mainly aerodynamic. The frequency split due to mistuning can cause that mode families’ interact due to reducing their frequencies separation. The advantage of the present method is that the effect of mode family interaction on aerodynamic damping and forced response is captured not being restricted to single mode families.
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Li, Bingqiang, Honggen Zhou, Jinfeng Liu, and Chao Kang. "Modeling and dynamic characteristic analysis of dual rotor-casing coupling system with rubbing fault." Journal of Low Frequency Noise, Vibration and Active Control, September 7, 2021, 146134842110393. http://dx.doi.org/10.1177/14613484211039322.
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With the rapid development of aero-engine manufacturing technology, the dual-rotor system has been employed in part of turbofan engine in order to improve the working performance of aircraft more efficiently. In this study, taking the counter-rotation dual-rotor as the research object, the dynamic model of dual rotor-casing coupling system is established by the aid of MATLAB. The dynamic frequency curves are in good agreement with the results in references and calculated by FEM method, that shows the validity and feasibility of the model. The local rub-impact dynamic model of dual rotor-casing coupling system is established, and rubbing analysis is carried out using Newmark- β method. The effects of rotating speed and speed ratio on local rub-impact response are deeply discussed. The results show that with the increase of rotating speed, combined frequencies and frequency multiplication components are more significant. In addition, speed ratio has a great influence on the periodic motion of the system. With the increase of the absolute value of the speed ratio, the whirl radius of the outer rotor and the normal rubbing force increase dramatically.